Rotatable center for lathes and grinders



pactly arranged.`

arranged insidefo'f the bull nose.

Patented Jan. 9, `1945 i 2,366,866,V c t no'rATALE CENTERFOR LATHES ANDc 4GRINDERS c Elmer` L. Rooie, Houston, Tex.`

I Anplinaiinn september 21, 19142, serial No. `isaoiiz iolaim. (o1. :i2-33) The invention relates to a 'center pointL for lathes and grinderswhich is adapted to sustain exceptionally heavy loads and whichiwillpermit high speed rotation of the work. i

Theusual center point which is noni-rotatable is of particulardisadvantage when heavy pieces burning. u i I i Variousrtypes ofrotatable center points v,have been heretofore devised bitjall of thesehave had certain disadvantages in failing to absorb a thrust suiiicientto support the load of the worker failing` to accuratelyalign thecenterpoint and prevent wiggle therein.

It is therefore one ofthe objects lof ,the present invention to providean exceptionally heavy duty `centerpoint capable of `sustaining Iloadsof approximatelyGOOO` pounds at high speed.

Another object of the invention is to provide are being handled or whenthe speed of rotation 1 is highbecause of the fact that the tremendousfriction betweenthe pointV and `the work causes case may be, isillustrated generally at 2 and has the usual recess 3 therein to receivethe center Ipoint construction.. The `center point `is made up of a bodyor` socket 4 having a shank 5 whose periphery i` `is provided with aMorse taper` so' as to provide a twith the recess 3. Ahead 8 forms apart of the socket 4 and` is considerably enlarged as best seen in Fig.1.

" This form` of center point in Fig. 1` iszanex- `ceptionally` heavyduty construction and is ca- In v pable of supporting loads of 60,0006pounds. order to accomplish this a sturdy, rigid structure is necessary`andfto thisend thehead is hollowed out to providea recess I: and theshank f 5` is `also hollow to 'provide anelongated recess `I I.

A shoulder I2 is arranged in the recess I0 adi `jacent thebase thereofand thisishoulder is ar.-

a rotating `center point which absorbs the thrust, l maintains alignmentand is capableof` running` in abath of oil. i

`Another object of the invention is to provide a double, combinationthrust andradial bearing for taking the load and maintaining alignmentVin a rotating center point. i

Still another object of the invention 'is to pro-` vide a lighter dutyrotating center `point where the thrust, `radial rand tail bearings` arecomi ,Another` object of the invention` is a ball, bearing` center pointwherein the Vtail bearing is disposedin the head of (the socket.- i-

` to provide i `Still another object of the ,invention 'is to provide abull nosev rotating center point wherein ine thrust and alignmentbearings are compactiy Other and further objects of the invention willbe readily apparent when the following description is considered inconnection with the accomi panying drawing wherein: y

Fig. 1 isa vertical sectional view of a `substantially heavy `dutycenter point illustrating the construction and arrangement of the center3 point bearing and socket. I

` Fig. `2 is a vertical sectional view of a somewhat lighter dutyrotating` center point wherein i all of the bearings are compactlyarranged` in the head of the socket.

Fig. 3 is a side elevation of abullnose type of center point wherein thebull nose and'barings are shown in section.

In Fig. the tail stock or ram thereof, as the ranged toreceive thecombination thrust and radial bearing I 4. This bearing is made up of lthe inside race I5, ball bearings I6 and the outer trace I] which hasthe thrust shoulder I8 thereon.

In orderA to` provide` for exact alignment of the center point anotherbearing 2,0is provided which 1 is identical with the bearing I4andsurmounts the bearingl so that there is a doublesupport i for thecenter spindle 22. These bearings I4 and f ZI)` are` firmly fitted uponthe cylindrical periphf ery 23 nf me spindle directly behind `the enlarged center point headportion 214.

` The tail portion 25 of the spindle is bearing 21. This bearing isarranged to abut a `shoulder 28 in thev recess II and is coni-ined onthe "reduced portion I2 of the center point shank by oneorlmoreretainerynuts 29. The end of i th'eushanli:` 5 is closed byia'capi) which isthread--` ed at 3l into the tapered end ,of` the recess II. jAroundtheheadZIlV of the center point aplate or retainermember 35 is threadedat 26 into the recess I0.

This plate carries a suitable packing 31 to form a seal about therotating center point spindle 22.

In view ofthe fact that the center point-can be assembled and is acomplete unit in and' of itself, it seems clear that the recess can vbelled .witlilubricant so that all of the bearings run` in oil. This is ofparticular advantagebecause `it voids wear and misalignment ofthe'parts.

" The positioning ofthe tail bearing a substantial distance from thethrust bearings lends itself to more accurate alignment, prevents.wiggle of` c reduced` atiZB and carries a double row anti-friction`tail This plate will be suitably threaded into position to firmlyconfine the bearings I 4 and 20 toforrn a seal with the spindle 22 andto i conne any lubricant which may be positioned i in the recesses I0and I I. i

the center point and the `fact that the center point is rotatable inbearings running in oil permits exceptionally high speeds of rotation ofthe work.

As above indicated center points constructed in accordance with therforegoing description have been made and actually used and havesupported loads of 60,000 pounds at high speed. This constitutes asubstantial .advance over other similar devicesiaeailableaon the market.

Fig. 2shows'a modied form v'of thecenterpoirit which is arranged forlighter loads approximating 20,000 or 30,000 pounds and is of slightlydifferent construction. The recessiintthe ram-0r tail stock isslightlysmaller than in Fig. 1.-;and accordingly the shank 5 of the tail stock 4is correspondingly smaller, in fact, the recess-'lll iisof such sizethat it does not permit-.thetcenter point spindle to extend thereintoand is closed by'a plug 40 threaded into the rear end'thereof. The

.head W8, is ,modied .somewhat .as `compared with lFig. .1 .andhas .a'shoulder 61 intermediate lthe .ends of 'therecessll which receives Lthecombi- Ynation radial and ,thrust bearings "Ii4 and 12'0 .whichare '.the`same as the` bearings `described inV lFig.;1 except vthat theyare;somewhatsmaller .1in .'si'ze. .The centerpointZ issomewhat diierentin that'beyond the cylindrical,periphery23which carries the bearings f4andfl2`0,the spin'dleis-,reduced at .63 to receive)the.`.tai1bearingl64. 4`This 'bearinglis a .radial .Lball,.bearingla-nd .is arranged Atoabut @the `seat '.65 `in the'base .of-the recess lll.

In rview of r,tl1e lfact that '.the .centerpoint .o'f '.Fig. 2 iis, notlintended fior ,asheavy .duty as .that ,of Fig j,l, the taillbearrighasLbeenpositioned rather rclose to 1the.main thrust bearing '.an'd ,a,suitable alignment .of the center point still `maintained.

.The plateandpacking'B'Larethe .same .as pre- ,viouslyfdescribed@Particular.attentionlisidirected to'.thefact. that the two bearings L4and 220 each..o"f the modications ,of .Lthe center polli-bare'independent bearings. Each .can.rdtate.- independently .of .the other.and 'this avoids iany marking ofthe .work

due .tolthelfact thatxthelbearings maybe .rotated together .as .is .the.usual Epractice. 'type Aof bearing is .generillylknown .to-the Ztrade..as;ad.u plexlbearng. They-may'begroundfand marked in pairsfor'ins'tallaton.

rotating .center .wherein ithe recess ..3 .in .the tram or tail stock.receives .,theashank '1U .of .the center point. spindle. vThebearingmonstructiondfEig.; 2 hasbeen somewhat .reduce'dlin;that..the,b.ul1.nose, cone onbell portion 11.! .is provided witha-recess 1.2 .a'n'dishoulder` '1.35 to' recever;thebearings L [4.. andZtl-,as well. as;theclosureplatesand packing 31. The;spin'dle'l1 0.sgre'duced atl'lto. receive. adouble row antie'friction 'tail'Jae'aring In .this .con-

n `v`closer the-'point of1support to 'the tail stoclthe struction thetail bearing is in addition to the main bearing due to the length of thebull nose "Il and tends to keep the nose in alignment. A plug 'I1 closesthe forward end of the bull nose and would tend to confine a body oflubricant therein.

All forms of the center point permit lubricant or oil to be confinedtherein so that the bearings run in oil. This oil can be admitted thruany of the giplugs shown or .it fcan be admitted thru a 'specialoil holeor plug not-shown.

A lubricated rotatable type of center point herein described permitsconsiderably higher speeds in .-turningrland grinding operationswithoutburning of the center points and while main-- .taining alignmentand avoiding wiggle. These lballibea'ring center points are moreaccurate un- .denloadfandipermt.three or four times the speed o'frotation o'f the work. While it is possible that .the :provision of thehead structure of this ron tatingpointcccupies a .slightly additional.length as .compared rwith the .conventional nonfroltating :centerpoint,r itseems 'obvious'.that. the.ram:.of..the tail stock" need notberun `.out -quite .as i'far when aroatingcenter pointis used. Thisarrangement lends itself to stability and alignmentlbecausethe of saidbearings and into .said shank, a shoulder at `the f tail of hsaid"shank, 'a 4tailcearing thereon 'fsupporting'the-spindle J"ta'iLmean'sthreaded .onto "the Espindle itail *to `load fallF of i'said bearings'by tightening thereon to "accuratelyjposition said "center-1 point f in-fthe .bearings,means to close the 'tail'of said'shankandnclose saidlast means, 'and a -iclosure-r for "said head includingv a singleannular plate threaded into said head "tojabut the cuter'dfrsaidbearings,'anda,packing 'ring Vcarried vby theiinncrjperiphery'ofsaid'plate tand sealing with the'jpeiiph'ery :df 'said ilange so that"thezin- 'teriorfoffthefsocketmay `retain.lubricant.in whichsaidrbearingsrmayrun.

